This application relates to nonaqueous electrolyte batteries, specifically to nonaqueous electrolyte batteries that use a nonaqueous electrolyte containing an organic solvent and an electrolyte salt.
Efforts have been made to reduce the size and weight of portable electronic devices such as camera-integrated VCRs, digital still cameras, cell phones, personal digital assistances, and laptop computers. In this connection, there has been active research and development to improve the energy density of batteries, particularly secondary batteries, used as the portable power source of such electronic devices.
Lithium ion secondary batteries that use carbon, a lithium-transition metal composite oxide, and a carbonate ester mixture for the negative electrode active material, the positive electrode active material, and the electrolytic solution, respectively, have been put to a wide range of practical applications for their ability to provide greater energy density than other nonaqueous electrolytic solution secondary batteries such as lead batteries and nickel cadmium batteries.
Laminated lithium ion secondary batteries that use an aluminum laminate film for the exterior particularly have high energy density because of lightness. Laminated polymer lithium ion secondary batteries also have widespread use among the laminated lithium ion secondary batteries, because the polymer used for the battery swells with the electrolytic solution, and suppresses deformation of the laminated battery.
JP-A-2003-331847 describes a battery that includes at least one carbon material having an average primary particle diameter of 10 to 100 nm, a binder such as polyvinylidene fluoride, and a vinylidene fluoride-hexafluoropropane copolymer, and a compound having a pyrrolidone skeleton, and in which the electrode blackness is 1.20 or more.
JP-A-2009-004227 describes a nonaqueous electrolyte battery provided with a positive electrode mixture layer configured to include one or more positive electrode active materials of olivine crystal structure, polyvinylpyrrolidone (PVP), and, optionally, a conductive auxiliary agent such as graphite, and a binder such as polyvinylidene fluoride (PVdF).